Brewing with Millet

NEIPA with 007 and Mandarina Bavaria Dry Hopped Under Pressure

Millet belongs to the same grass family as barley, maize, and sorghum. It’s said to be a versatile crop because of its ability to thrive in harsh conditions. One source mentioned that millet is one of the oldest crops known to humans, possibly dating back to 2800 B.C! There are numerous varieties of millet, with proso millet (Panicum miliaceum L.) “common millet” is likely what you will find at a place like Whole Foods or a local organic market in bulk (this is what I was able to find). There doesn’t appear to be a vast amount of research done on brewing with millet, but from what I could locate, it does appear to produce acceptable beers. Across the literature, millet was often compared very closely to sorghum, which has been used in many parts of the world mainly in European-type lagers.

One reason some might want to experiment brewing beers with millet is because it’s gluten-free. Other carb-rich grains that could be used in brewing that don’t contain gluten are buckwheat, amaranth, and quinoa (I’ve experimented with quinoa with good results, although as a part of a barley grist). Oats can be tolerated by most, but not all people intolerant to gluten. The gluten content of beers is fairly low considering the high amounts present early in the brewing process (6,864 ppm present in wort going all the way down to around 200ppm in finished beer or around 1.9%).1

High Gelantinzation Temperature

Although the gelatinization temperature will likely slightly change with different varieties, overall, millet has a very high gelatinization temperature compared to most grains. In a study of over 20 varieties, the range was from 168ºF-173ºF.2 Because this range is warmer than typical mashing temperatures, a cereal mash would have to be performed. In my case, I simply boiled the millet for 10 minutes, drained, and added directly to the mash. Make sure to properly adjust the mash-in temperature to account for the recently boiled warm grains.

Color & Head Retention

A study looking at lager beers brewed with millet (pennisetum maiwa), sorghum and barley malts found that the millet beers were darker in color than barley and sorghum beers (5.3 SRM to 3.5 SRM for the barley beer). Maybe most important, the millet beers were scored lower than both the sorghum and barley beers with tasters. 3 I too saw a darker than usual color in the experimental beer I brewed with millet outlined below. The authors weren’t quite sure why they saw a higher color with millet but mentioned it’s possible the reason was a higher tannin in millet. The millet beer had better head retention than sorghum, but not the barley beer. This could be because millet varieties tend to have decent protein counts, which are around 11.3%-12.7% compared to 9.5%-11.5% for most pale barley malts.4 This Agu study also found 66.8% attenuation limit with millet compared to 88% from the barley.

Extract Potential & Soluble Nitrogen

Zarnkow found the average extract content from millet to be lower of barley (76-85% for barley to 43%-63% for millet). This could be because millet has a much higher husk content than barley. So if you are going to make up a large percentage of your grist with millet, you should probably take into consideration a loss in your typical expected mashing efficiency. Poor filtration rates were also reported with millet beer, due to the low beta glucanase developed when malted.

Zarnkow also reported the soluble nitrogen was lower in millet than in barley. Barley malts are typically measured around 600-900 mg/100 g, millet was found to have 368-561 mg/100 g (averaged 457 mg/100 g across all the varieties tested). Soluble nitrogen is important for head retention and for increased mouthfeel. As I mention in my tasting notes for my experimental beer with millet, I noticed a thinner mouthfeel than I typically get with similar style beers, although the head retention was similar.

Mash Run-Off

In my experimental beer brewed with 25% unmalted millet, I had a hell of a time with stuck sparge. This, of course, isn’t a big deal if you mash with a fine mesh bag or utilize rice hulls. For comparison purposes, when I brewed a beer with 40% unmalted oats, I had a much smoother runoff. Although detailed for sorghum in a study, which millet closely resembles, this was likely due to varying percentage of branching in starch amylopectin and to varying bonding forces in the granules.5 Interestingly, tested viscosity values for millet were actually lower than of barley.

Fermentation

Wort made from lots of millet will be high in glucose, which could lead to fast fermentations because of yeast ability to ferment this quickly. One study fermented a beer with 100% malted proso millet and found fermentation was effectively over after just two days. This particular study found that millet beers fermented basically as expected with a champagne, altbier, kölsch, and Brettanomyces bruxellensis strains.6

Malted millet (Sossat) was found to produce an appropriate amount of amino acids required for fermentation as well as the optimal development of diastatic power and soluble nitrogen.7

Home Malting Millet

Because malted millet is likely hard to come by, you could try malting it yourself at home (or just use it raw like I did!). You can order malted millet online (even crystal millet!), Gluten Free Homebrewing has a great selection. If you do try home malting it, a good germination temperature would be around 71°F and hold for a few days. You might see higher diastatic power if you increase the germination time (from 2-6 days). A good kilning temperature and duration appear to be around 122°F for 18 hours.8 Muoria also noted that malted millet had a saccharification time of 20 minutes, which is slower than typical well-modified barley malts (10-15 minutes), but not a dealbreaker.

Millet NEIPA with 007 and Mandarina Bavaria

Idid some research and brewed an experimental beer awhile back on fermenting and dry hopping under pressure. I noted that the experiment led me to want to try this again, but with a few adjustments. That is to do a combination of a cool non-pressure ferment with capping the fermenter only after adding the first dry hop charge to attempt to trap in all of the hop aromatics.

So, for this beer, I did the primary fermentation in a 10-gallon keg. Because I like to dry hop with loose pellets (not bagged) I put a stainless steel filter over the dip tube, which would allow me to dump in the dry hops loose and still be able to transfer the beer via C02 without clogging things up. Because there is so much headspace in a 10-gallon keg when brewing a 5-gallon batch, I didn’t worry about a blowoff tube. Instead, I simply left the pressure relief valve open, mimicking in a small way an open ferment, which may help get rid of DMS and potentially keep esters in check.

Behind the C02 haze, here is the filter over the dip tube in the fermenter.

I’m excited about this setup for fermenting hoppy beers, in addition to the pressure dry hop (hopefully trapping aromatics), I’m able to transfer the beer with C02 and never expose the beer to oxygen when going into another purged serving keg (with more hops!). With the help of a spunding valve, another benefit is watching the valve during the tail end of fermentation. As soon as the gauge stops going up, you know it’s essentially done fermenting. In my case, this was around 20-22 psi, which also meant the beer had a head start on carbonation!

I took the no oxygen process a step further when adding the dry hops on day 5 of fermentation by hooking up the C02 to the keg with a constant 5 PSI continually flushing the headspace during the time I opened the keg to put in the dry hops. After closing the keg back up, I left the pressure on and purged the keg twice and seal again. This idea came from a recent MBAA study where the authors dry hopped beers with continuous flushing of the headspace with 5-10 psi of C02, which they noted could contribute to reduced variability in the aroma intensity of dry hopping beers caused by oxygen.9

Thanks to my friend Mike Tonsmeire for the package of 007: The Golden Hop, having had and really enjoyed his hoppy sour beer brewed with it, I had to give it try! The 007 hop is described as coming across as ripe with zesty oranges and tangerines reminiscent of marmalade. Because I’m usually underwhelmed with single hop beers, I wanted to pair 007 with another hop to build a more complex hop profile. The Hop Compendium describes Mandarina Bavaria with fruity characteristics of pineapple, lemon, gooseberry, cassis, strawberry, redcurrant, and pepper. The hope is these two varieties would pair nicely with each other!

I was a little surprised to see how much the millet seem to darken the beer. Compared to a similar beer’s I’ve brewed swapping the millet for oats or spelt, it’s noticeably a couple shades darker. With the haziness that comes with the NEIPA and the slightly darker shade, it really comes across as a rustic beer. Perhaps this is why I’ve seen Millet showcased in saisons. If you or your beer consumers are sensitive with appearance, this could be an issue with millet as my beer kind of resembled dirty dishwater (rustic sounds better!).

For only using four total ounces of dry hops, it has a potent fresh hop aroma. I’m starting to think you can get by with fewer hops when combining loose dry hops in a sealed environment. I get a lot of orange fruits in the aroma. I’d agree with any of the major orange citrus fruit descriptors here: blood oranges, clementines, tangerines, and mandarin oranges. There is also a pretty potent hop spice character cutting through the citrus. I could see somebody describing this spice as being a little dank even.

The biggest differences I’m noticing with the high millet used compared to similar NEIPA’s without the millet is a slightly thinner mouthfeel, increased dryness (lower final gravity), and slightly more alcohols in the aftertaste. I probably should have mashed this much higher or even gone with a water build of 100% chloride. I’m not sure why there seem to be more alcohols in the flavor, but as the beer warms, this stands out to me even more. It’s not aggressive, but I’d prefer it toned down (especially paired with a spicy hop character).

It also seems like this beer has less of an ester profile than I’m used to with this yeast. I’m wondering if this wasn’t both the result of capping the fermentation prior to it being over (esters still being formed) as well as raising the temperature on day 5, which may also lower esters. I’m still questioning the best time to cap fermentation, I want to take advantage of active fermentation to help get rid of oxygen from dry hopping as well as try to get bioflavoring from the hop and yeast interaction, but also don’t want to trap any unwanted early fermentation characteristics into the beer or greatly reduce the esters from the pressure. Perhaps dry hopping early or even before fermentation (pre-fermentation hops) combined with a small 3-day dry hop (not yet under pressure), followed by another small dry hop around day 6-7 and capping fermentation would be best.

Overall it’s a really nice beer and a good first attempt with using millet. Flavor wise it’s difficult to say what the millet is bringing, but this is probably more because all of the hops used than anything. I’m very happy with this dry hopping and transferring technique. I’ll be using the 10-gallone keg for the next hoppy beer, that’s for sure!

Agu, R. C., & Palmer, G. H. (2013). Evaluation of the potentials of millet, sorghum, and barley with similar nitrogen contents malted at their optimum germination temperatures for use in brewing. Journal of the Institute of Brewing, 119(4), 258-264. doi:10.1002/jib.91

13 Comments

Lyle
on November 10, 2016 at 10:10 pm

Hi Scott, I have been loving your articles! I have a quick question for you about dry hopping and pH. I have a NE pale ale (1.053) fermenting right now – I used 4 oz. CItra in the whirlpool, added 8 oz. Citra on day 3, and plan to add 4 oz. Citra in the keg. I have read that heavy dry hopping can raise the final pH of beer in large amounts. It doesn’t look like you have dry hopped this much, but I wondered if you ever considered adding lactic acid to counteract this. Thanks for any advice! – Lyle

Thanks! Wow, that’s a ton of hops! Your right, heavy dry hopping like that will likely increase the final beer pH (it’s about 0.28 per 5 ounces of dry hops). Interestingly it has been found that beers with the same iso-alpha-acid content actually tasted more bitter as the pH increased. However, with extreme heavy dry hopping like you are doing, that will actually pull some of the iso-acids out of the beer and although it’s replaced with less-bitter humulinones, you’ll actually see a reduction in IBUs with your dosage. This is all to say, I wouldn’t worry about adjusting for the pH, although it might increase a bit and taste more bitter, you will also lose some IBUs, which would be less bitter.

Do you find the beer stays “juice” like longer when you’ve packaged it with your new process?

One of my favorite things is the hydrometer sample when I keg my pale ales. They have an orange juice/pineapple/fruit juice thing that fades in a day or two. I’ve had quite a few NEPAs and even those don’t capture the “juice” flavor from an extremely fresh pale ale. I understand the “juiciness” that people describe in these beers BUT it’s not the same “juice” flavor that comes from that 8-10 day old pale ale sample.

A friend recently started getting his conicals dialed in to the point of eliminating O2 from his entire process. His last pale ale stayed in that “juice” zone for about a week after packaging.

Love the idea of the “juice zone,” I actually would say this particular beer had more of that fresh hop character for longer, which I can only hope was in part to the closed c02 transfers and dry hopping. We’ll see how future beers go with the same process.

I fermented a 1.060 pale ale that went 4 days from brew night before I close transferred it last night (day 4) onto some hops in a purged keg with a spunding valve attached. I left the spunding valve at 30psi before going to bed but when I woke up there was no movement of the valve needle…maybe a slight bit as it’s not resting on the zero stop but it’s not registering any pressure. I thought for sure I’d get more activity. This is the first time using my spunding valve….I pressure checked it and it worked fine. I’d assume at day 4 I’d still have some fermentation going on and that there would have been some increase in pressure. The blow off tube was burping every 30 seconds or so before doing the transfer.
Any thoughts on this?

Thanks for your response. No. The empty keg was fine…it held 30lbs of pressure while purging it to get it ready. When I filled it I didn’t repressurize it as I figured the still fermenting beer would repressurize it.
When I got home from work this afternoon the pressure had finally started to build (it was just north of 2psi). As of writing this it’s just shy of 5psi on the spunding valve.

Did you do anything to the millet before you did your cereal mash? A lot of articles seem to have their cereal mashes focus on Rice and Corn, where the grains are crushed into finer particles before starting this mash step.

G’Day Scott,
Great write up, as you appreciate there are precious little other articles out there on this subject and I’ve been interested in doing a Millet beer, but for the purpose of making a Whisky from it ever since I’ve had a fleeting taste Koval Millet Whisky.
What advice would you have for me?

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